Multi-image projector and electronic device having multi-image projector

ABSTRACT

The present invention provides a projector including a laser module and a lens module, wherein the lens module includes a plurality of lens and a plurality of diffractive optical elements. In the operations of the projector, the laser module is arranged to generate at least one laser beam; each of the lenses is arranged to receive one of the at least one laser beam to generate a collimated laser beam; and the diffractive optical elements correspond to the lenses, respectively, and each of the diffractive optical elements is arranged to receive the collimated laser beam from the corresponding lens to generate an image. The images generated by the diffractive optical elements form a projected image of the projector. By using the projector of the present invention, the projected image may have higher resolution or field of view that is advantageous for the 3D sensing system.

CROSS REFERENCE TO RELATED APPLICATIONS

This divisional application claims the benefit of co-pending U.S. patentapplication Ser. No. 16/142,003, filed on Sep. 26, 2018, andincorporated herein by reference.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to a projector, and more particularly, toa multi-image projector applied in a 3D sensing system.

DESCRIPTION OF THE PRIOR ART

In order to obtain 3D images, an electronic device may use a projectorfor projecting a special pattern to a surrounding region, and use camerato capture the image having the special pattern, and the captured imageis analyzed by a processor to obtain the depth information of the image.The conventional projector has a fixed focal length and a fixed field ofview (FOV), so if the special pattern is projected to an object that isfar away from the projector or too close to the projector, a resolutionof the special pattern may be worsened and the depth information may notbe accurately determined.

SUMMARY OF THE INVENTION

It is therefore an objective of the present invention to provide aprojector, which can generate the appropriate projected image to thesurrounding region based on the working distance of the projector, tosolve the above-mentioned problems.

According to one embodiment of the present invention, a projectorincluding a laser module and a lens module is provided, wherein the lensmodule includes a plurality of lens and a plurality of diffractiveoptical elements. In the operations of the projector, the laser moduleis arranged to generate at least one laser beam; each of the lenses isarranged to receive one of the at least one laser beam to generate acollimated laser beam; and the diffractive optical elements correspondto the lenses, respectively, and each of the diffractive opticalelements is arranged to receive the collimated laser beam from thecorresponding lens to generate an image.

According to another embodiment of the present invention, an electronicdevice is provided, wherein the electronic device includes a projector,a camera module and a processor. In the operations of the electronicdevice, the projector is arranged to generate a projected image to asurrounding environment, the camera module is arranged to capture aregion of the surrounding environment to generate image data, and theprocessor is arranged to analyze the image data to obtain depthinformation of the image data. In one embodiment, the projector includesa laser module and a lens module, wherein the lens module includes aplurality of lens and a plurality of diffractive optical elements. Inthe operations of the projector, the laser module is arranged togenerate at least one laser beam; each of the lenses is arranged toreceive one of the at least one laser beam to generate a collimatedlaser beam; and the diffractive optical elements correspond to thelenses, respectively, and each of the diffractive optical elements isarranged to receive the collimated laser beam from the correspondinglens to generate an image. The images generated by the diffractiveoptical elements form the projected image of the projector.

These and other objectives of the present invention will no doubt becomeobvious to those of ordinary skill in the art after reading thefollowing detailed description of the preferred embodiment that isillustrated in the various figures and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating an electronic device according to oneembodiment of the present invention.

FIG. 2 is a diagram illustrating the projector according to oneembodiment of the present invention.

FIG. 3 shows the laser module according to the embodiments of thepresent invention.

FIG. 4 shows the laser module according to other embodiments of thepresent invention.

FIG. 5 shows generating the projected image according to one embodimentof the present invention.

FIG. 6 shows the use of the projector when the lenses are designed tohave different focal lengths according to one embodiment of the presentinvention.

FIG. 7 shows a laser module and a lens module according to anotherembodiment of the present invention.

FIG. 8 shows the laser module shown in FIG. 7 according to oneembodiment of the present invention.

DETAILED DESCRIPTION

FIG. 1 is a diagram illustrating an electronic device 100 according toone embodiment of the present invention. As shown in FIG. 1 , theelectronic device 100 comprises a projector 110, a camera module 120, aprocessor 130 and a controller 140. In this embodiment, the electronicdevice 100 may be a smart phone or a pad or any other portable devicecapable of generating 3D images.

In the operation of the electronic device 100, when the electronicdevice 100 prepares to capture a 3D image of an object 102, firstly, theprocessor 130 notifies the controller 140, and the controller 140controls the projector 110 to generate a projected image 104 to theobject 102. Then, the camera module 120 captures the projected image 104with the object 102 to generate image data. Then the processor 130analyzes the image data to obtain the depth information of the imagedata to generate the 3D image. As mentioned in the background of theinvention, the resolution of the projected image 104 may be worsened ifthe object 102 is far away from the projector 110 or the object 102 istoo close to the projector 110. Therefore, the embodiments of thepresent invention provide some designs of the projector 110 to make theprojected image 104 on the object 102 have the better resolution or FOV.

FIG. 2 is a diagram illustrating the projector 110 according to oneembodiment of the present invention. As shown in FIG. 2 , the projector110 comprises a laser module 210 and a lens module 220, where the lensmodule 220 comprises a substrate 221, two lens 222_1 and 222_2 imprintedon a surface of the substrate 221, a substrate 225, two diffractiveoptical elements (DOE) 224_1 and 224_2 imprinted on a surface of thesubstrate 225, and spacers 223. In this embodiment, the laser module 210may be a package having at least one infrared laser diode for emittingone or two infrared laser beams (FIG. 2 shows two laser beams, not alimitation of the present invention), and one laser beam passes throughthe substrate 221, the lens 222_1, the DOE 224_1 and the substrate 225to generates a first image having a pattern of the DOE 224_1, and theother laser beam passes through the substrate 221, the lens 222_2, theDOE 224_2 and the substrate 225 to generates a second image having apattern of the DOE 224_2. It is noted that the first image or the secondimage can be simultaneously or sequentially generated, or only one ofthe first image and second image is generated according to thedesigner's consideration. For example, the when the first image and thesecond image are simultaneously or sequentially generated, the firstimage and the second image form the projected image 104 of the projector110.

In one embodiment, the infrared laser diode may be edge emitting type,plasma laser diode or surface emitting type such as a vertical-cavitysurface-emitting laser (VCSEL). In addition, the lenses 222_1 and 222_2may have the same focal length or different focal lengths.

The arrangements of the layers shown in FIG. 2 are for illustrativepurpose only, as long as the lens module 220 is capable of generatingthe first image and the second image, the lens module 220 may havedifferent designs. For example, the lens 222_1 or 222_2 may be abiconvex lens, or another lens may be positioned above the lens 222_1 or222_2, or the DOEs 224_1 and 224_2 may be imprinted on the upper surfaceof the substrate 225. In addition, the substrate 225 may have a singleDOE layer, and the DOE 224_1 is a left portion of the DOE layer, and theDOE 224_2 is a right portion of the DOE layer. These alternative designsshall fall within the scope of the present invention.

FIG. 3 shows the laser module 210 according to the embodiments of thepresent invention. As shown in FIG. 3(a), the laser module 210 comprisesa submount 310 and two laser diodes 312 and 314, wherein the laserdiodes 312 and 314 are bonded on the same side plane of the submount310. In this embodiment, the laser beam generated by the laser diode 312passes through the DOE 224_1 of the lens module 220 to generate thefirst image, and the laser beam generated by the laser diode 314 passesthrough the DOE 224_2 of the lens module 220 to generate the secondimage. In the embodiment shown in FIG. 3(b), the laser module 210comprises a submount 320 and two laser diodes 322 and 324, wherein thelaser diodes 322 and 324 are bonded on the different side planes of thesubmount 320. The laser beam generated by the laser diode 322 passesthrough the DOE 224_1 of the lens module 220 to generate the firstimage, and the laser beam generated by the laser diode 324 passesthrough the DOE 224_2 of the lens module 220 to generate the secondimage. In the embodiments shown in FIG. 3 , the first image and thesecond image are overlapped when they are projected on the object 102.

FIG. 4 shows the laser module 210 according to other embodiments of thepresent invention. As shown in FIG. 4(a), the laser module 120 comprisesa submount 410, a laser diode 412 and two prisms 414 and 416, wherein aportion of a laser beam generated by the laser diode 412 is reflected bythe prism 414, and another portion of the laser beam passes through theprism 414 and is reflected by the prism 416. The laser beam reflected bythe prism 416 passes through the DOE 224_1 of the lens module 220 togenerate the first image, and the laser beam reflected by the prism 414passes through the DOE 224_2 of the lens module 220 to generate thesecond image. In the embodiment shown in FIG. 4(b), the laser module 120comprises a submount 420, a laser diode 422, two prisms 424 and 426 anda lens 428, wherein a portion of a laser beam generated by the laserdiode 422 passes through the lens 428 and is reflected by the prism 424,and another portion of the laser beam passes through the lens 428 andthe prism 424 and is reflected by the prism 426. The laser beamreflected by the prism 426 passes through the DOE 224_1 of the lensmodule 220 to generate the first image, and the laser beam reflected bythe prism 424 passes through the DOE 224_2 of the lens module 220 togenerate the second image. In the embodiments shown in FIG. 4 , thefirst image and the second image are overlapped when they are projectedon the object 102.

FIG. 5 shows generating the projected image 104 according to oneembodiment of the present invention. As shown in FIG. 5 , one laser beampass through the DOE 224_1 of the lens module 220 to generate the firstimage 502 to the object 102, and another laser beam pass through the DOE224_2 of the lens module 220 to generate the first image 504 to theobject 102, where each of the first image 502 and the second image 504have a plurality of light spots. The positions of the first image 502and the second image 504 can be carefully designed to make the projectedimage 104 including the first image 502 and the second image 504 havehigher light spot density (i.e. high resolution) as shown in FIG. 5 .

It is noted that the patterns shown in FIG. 5 are for illustrativepurposes only, and they are not limitations of the present invention.For example, the patterns of the first image 502 and the second image504 (i.e. the patterns of the DOE 224_1 and 224_2) may be the same ordifferent, and the density/resolution of the first image 502 and thesecond image 504 may be the same or different. In addition, theembodiment shown in FIG. 5 shows that the whole areas the first image502 and the second image are almost overlapped, however, the overlapratio of the first image 502 and 504 may be designed according toengineer's consideration. For example, the projector 110 can be designedto make only the left portion of the first image 502 and the rightportion of the second image 504 be overlapped. These alternative designsshall fall within the scope of the present invention.

FIG. 6 shows the use of the projector 110 when the lenses 222_1 and222_2 are designed to have different focal lengths according to oneembodiment of the present invention. As shown in FIG. 6 , the lens 222_1has the focal length f1, and the lens 222_2 has the focal length f2, forexample, f1 may be 0.2 meter while f2 is equal to 0.5 meter. In thisembodiment, when the object 102 is close to the projector 110 (e.g. 0.15meters), the first image outputted by the DOE 224_1 may be clear, andwhen the object 102 is far from the projector 110 (e.g. 0.75 meters),the first image outputted by the DOE 224_1 may be blurry. On the otherhand, when the object 102 is close to the projector 110, the secondimage outputted by the DOE 224_2 may be blurry, and when the object 102is far from the projector 110, the first image outputted by the DOE224_2 may be clear. Therefore, since each of the lenses 222_1 and 222_2has its corresponding working distance, the electronic device 100 canselect one of the second image and the second image having clearpatterns, and analyze the selected one to obtain the depth informationof the projected image 104.

Regarding the control of the projector 110 shown in FIG. 6 , the firstimage and the second image may be sequentially generated to the object102, and the camera module 120 captures the image data corresponding tothe first image and the second image, respectively, and the processor130 determines which one of the first image and the second image is moreclear, and the processor 130 selects and analyzes the clear one toobtain the depth information of the projected image. In otherembodiments, the electronic device 100 may use other elements or methodscapable of measuring the distance between the electronic device 100 andthe object 102, and the controller 140 controls the projector 110 togenerate the image corresponding to the lens whose focal length iscloser to the measured distance. Taking FIG. 3(a) and FIG. 6 as anexample, if the electronic device 100 determines that the distancebetween the electronic device 100 and the object 102 is small, thecontroller 140 may control the projector 110 to turn on the laser diode312 to generate the laser beam to the lens 222_1 and the DOE 224_1 togenerate the first image, meanwhile the laser diode 314 is turned off.If the electronic device 100 determines that the distance between theelectronic device 100 and the object 102 is great, the controller 140may control the projector 110 to turn on the laser diode 314 to generatethe laser beam to the lens 222_2 and the DOE 224_2 to generate thesecond image, meanwhile the laser diode 312 is turned off.

The embodiments 110 shown in FIGS. 2-6 only show two lenses 222_1 and222_2 and two DOEs 224_1 and 224_2, however, the quantity of the lensesand the DOEs may be more than two (e.g. 1*N array, M*1 array, M*N array,where M and N are any suitable integers). FIG. 7 shows a laser modulecomprising a submount 710 having four laser diodes 712, 714, 716 and 718bonded thereon, and a lens module comprising four DOEs 724_1-724_4. Inthe embodiment shown in FIG. 7 , the laser diode 712 is arranged togenerate a laser beam to the DOE 724_1 to generate a first image, thelaser diode 714 is arranged to generate a laser beam to the DOE 724_2 togenerate a second image, the laser diode 716 is arranged to generate alaser beam to the DOE 724_3 to generate a third image, and the laserdiode 718 is arranged to generate a laser beam to the DOE 724_4 togenerate a fourth image. In the embodiment shown in FIG. 7 , the laserdiodes 712, 714, 716 and 718 can be simultaneously turned on orsequentially turned on, or only a portion of the laser diodes 712, 714,716 and 718 is/are turned on according to a working distance. Because aperson skilled in the art should understand the operations andapplications of the embodiment shown in FIG. 7 after reading theaforementioned embodiments, further descriptions are omitted here.

FIG. 8 shows the laser module shown in FIG. 7 according to oneembodiment of the present invention. As shown in FIG. 8(a), the lasermodule comprises a submount 810, two laser diodes 812 and 814, and twoprisms 816 and 818, wherein a portion of a laser beam generated by thelaser diode 812 is reflected by the prism 816, and another portion ofthe laser beam passes through the prism 816 and is reflected by theprism 818; a portion of a laser beam generated by the laser diode 814 isreflected by the prism 816, and another portion of the laser beam passesthrough the prism 816 and is reflected by the prism 818. The laser beamgenerate by the laser diode 812 and reflected by the prism 816 passesthrough the DOE 824_1 of the lens module to generate the first image,the laser beam generate by the laser diode 814 and reflected by theprism 816 passes through the DOE 824_2 of the lens module to generatethe second image, the laser beam generated by the laser diode 812 andreflected by the prism 818 passes through the DOE 824_3 of the lensmodule to generate the third image, and the laser beam generated by thelaser diode 814 and reflected by the prism 818 passes through the DOE824_4 of the lens module to generate the fourth image. In the embodimentshown in FIG. 8(b), the laser module comprises a submount 830, two laserdiodes 832 and 834, two prisms 836 and 838, and two lenses 839_1 and839_2, wherein a portion of a laser beam generated by the laser diode832 passes through the lens 839_1 and is reflected by the prism 836, andanother portion of the laser beam passes through the lens 839_1 and theprism 836 and is reflected by the prism 838; a portion of a laser beamgenerated by the laser diode 834 passes through the lens 839_2 and isreflected by the prism 836, and another portion of the laser beam passesthrough the lens 839_2 and the prism 836 and is reflected by the prism838. The laser beam generate by the laser diode 832 and reflected by theprism 836 passes through the DOE 824_1 of the lens module to generatethe first image, the laser beam generate by the laser diode 834 andreflected by the prism 836 passes through the DOE 824_2 of the lensmodule to generate the second image, the laser beam generated by thelaser diode 832 and reflected by the prism 838 passes through the DOE824_3 of the lens module to generate the third image, and the laser beamgenerated by the laser diode 834 and reflected by the prism 838 passesthrough the DOE 824_4 of the lens module to generate the fourth image.

Briefly summarized, in the projector of the present invention, theprojector is capable of generating a plurality of images, and the imagesmay be generated simultaneously or sequentially to obtain the projectedimage with higher density/resolution and/or FOV, or only part of theimages is/are generated based on a distance of the projector and theobject to obtain the clearer projected image.

Those skilled in the art will readily observe that numerousmodifications and alterations of the device and method may be made whileretaining the teachings of the invention. Accordingly, the abovedisclosure should be construed as limited only by the metes and boundsof the appended claims.

What is claimed is:
 1. A projector, comprising: a laser module, forgenerating at least one laser beam; a lens module, comprising: at leastone lens, arranged to receive the at least one laser beam to generate acollimated laser beam; a plurality of diffractive optical elements,wherein each of the diffractive optical elements is arranged to receivethe collimated laser beam from the lens to generate an image; a firstprism disposed in front of the lens, wherein the first prism receivesthe collimated laser beam and reflects a first portion of the collimatedlaser beam to a first diffractive optical element of the plurality ofdiffractive optical elements, and a second portion of the collimatedlaser beam passes through the first prism; and a second prism disposedbehind the first prism, wherein the second prism receives the secondportion of the collimated laser beam and reflects the second portion toa second diffractive optical element of the plurality of diffractiveoptical elements; wherein the laser module comprises at least one laserdiode, and the at least one laser diode is arranged to generate aplurality of laser beams to the lens.
 2. The projector of claim 1,wherein a quantity of the laser diodes is less than a quantity of thediffractive optical elements.
 3. The projector of claim 1, furthercomprising: a second laser diode for generating a second laser beam; anda second lens arranged to receive the second laser beam to generate acollimated second laser beam; wherein the first prism receives thecollimated second laser beam and reflects a first portion of thecollimated second laser beam to a third diffractive optical element ofthe plurality of diffractive optical elements, and a second portion ofthe collimated second laser beam passes through the first prism; whereinthe second prism receives the second portion of the collimated secondlaser beam and reflects the second portion of the collimated secondlaser beam to a fourth diffractive optical element of the plurality ofdiffractive optical elements.